Study of the Jovian [S II] nebula at high spectral resolution

Observations of [S II] lambdalambda6716--6731 emissions from the Jovian magnetosphere have been carried out with a PEPSIOS spectrometer at the Hale 5 m telescope. Spectral resolving power was sufficient resolve the [S II] line widths. From measured lambdalambda6716--6731 doublet rations and spectral line widths we found a thermal plasma characterized by temperatures approx.2 x 104 K and electron densities approx.2 x 103 cm-3. The source of [S II] emissions was centered within a toroidal region of radius 5 R/sub j/ (inside the orbit of Io), with tigh latitudinal confinement near the equilibrium equator for ions in the tilted corotating Jovian magnetic field, and significant long-lived longitudinal structure